Theoretic Analysis of Optical Fiber Ring Resonators Based on A Collinear 3×3 Fiber Coupler

We present a systemic theoretical analysis of three different types of optical fiber ring resonator using a collinear 3×3 fiber coupler. It is the first time that the theoretical analysis of dual ring resonator based on a collinear 3×3 fiber coupler is presented. Expressions for the output fields and output intensities of the fiber ring resonator are obtained. By using computer system software one can obtain these output intensities easily. The three types of resonators all use a collinear 3×3 fiber coupler as key device in which the three fibers are in the same plane. It is found that these fiber ring resonators have their own special characteristics. They can be used as fiber filter, a sensor with high_phase sensitivity and densely spaced two_channel wavelength division multi/demultiplexer(WDM/WDDM).